The subject of shipbuilding in the Mediterranean during the Middle Ages is an integral aspect of the maritime history of this region. Characterized primarily by a fundamental shift in shipbuilding techniques, this phase also included significant developments in other seafaring practices. Yet, unlike the preceding Byzantine era, there is a very limited body of archaeological evidence available for study which can be utilized to illustrate these changes. Therefore, one must turn to alternative sources of information regarding the construction of ships in the Mediterranean, such as iconography and literary evidence. Perhaps the most informative and useful example of the latter is the group of nautically-themed treatises and manuscripts composed between the 14th and 16th centuries. The earliest of these to describe ship construction in any detail is the 1434 manuscript of Michael of Rhodes, which will serve as the main subject of study for this thesis. The primary purpose of this research is to propose a reconstruction of the nave quadra described in the manuscript, though this will be preceded by explanations of several topics pertinent to ship construction in the Mediterranean during the Middle Ages. The discussion of such fundamental issues, like the transition from shell-based to frame- based construction and the concept of recording and conveying these processes in a didactic manner, is essential in providing a basis for this study. Once this foundation has been established, it will then be possible to present the reconstruction of the nave quadra of the Michael of Rhodes manuscript. With this background information laid out, the significance of both the manuscript and the nave quadra in the broader context of medieval seafaring in the Mediterranean should be discernable. In addition to the proposed reconstruction, this task of elucidating key aspects such as the transition from one construction technique to another and the compilation of written material on this subject will be essential to providing as comprehensive a picture of medieval seafaring in the Mediterranean as possible.

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1. The literature concerning the dispersion off collagen by concentrated salt solutions has been reviewed; the literature concerning the reconstitution off native type collagen fibres has boon briefly reviewed, as has recent literature on the properties off the substrate for this work, calf skin collagen. 2. It has been shown that the dispersion off collagen by KI and CaCl2, involves, above a threshold concentration off salt, a highly reversible denaturation of the protein. 3. This denaturation has been shown to result in the dissociation off collagen into three subunits at various concentrations off salt. It has been proposed on the basis of these fractionations that the collagen employed consists off a population off units with varying degrees off resistance to depolymerisation, and therefore varying degrees off intramolecular cohesion. 4. It is considered that the available evidence favours as the mechanism off denaturation the reorientation off water in the solvent by KI or CaCl2 rather than the direct binding off salt molecules or ions to the protein. 5. Collagen fibres thermally reconstituted in the presence of various physiological substances have been shown to have different degrees of resistance to re-dispersion by KI and urea. Substances which appear to render the collagen more resistant are some anions, all amino acids tested, and L-ascorbic acid. 6. The effect of ascorbic acid and related substances on the resistance to re-dispersion of thermally reconstituted collagen has been studied in some detail and it is considered that the stabilising effect of this substance is due to its ionising enol grouping. The literature concerning a possible interaction of L-ascorbic acid with collagen in vivo has been reviewed and it has been proposed that the acid may have both an intracellular and extracellular function in repair tissue. 7. It has been demonstrated that non-protein nitrogen can be prepared from collagen in a number of ways, some of which do not involve extremes of pH or temperature throughout the entire manipulation of the collagen, Evidence for and against the assigning of a specific biological function to this non-protein nitrogen has been discussed.

1. The literature on the egg white proteins has been reviewed. 2. The individual egg white proteins have been isolated and the methods used described. 3. The possible origin of these proteins has been discussed. An attempt has been made to elucidate this problem by refined electrophoretic techniques. No definite conclusion could be reached with the methods available. 4. The N-terminal residues of the individual proteins were examined and the results found to be in good agreement with the literature. 5. The structure of the native ovalbumin molecule has been examined by both chemical and physical means during progressive denaturation in alcohol, urea and guanidine hydrochloride. The results of the two investigations were shown to be in agreement with one another. 6. A 'six-shaped' structure has been proposed for the configuration of the native ovalbumin molecule. 7. This structure involves the hypothesis of an intra-molecular link since there is known to be a C-terminal, but no N-terminal amino acid residue. The disulphide bridge suggested by Anfinsen and Redfield (1956) hg.B been shown to be unlikely. This link has not been identified as a chemical entity although it has been suggested that low pH enables hydrogen bond breakers to rupture the molecule more easily.

1. YADH was immobilised on two aminoethylcelluloses and their properties were compared. 2. Experimental conditions for the coupling of YADH to Cellex-AE were optimised; these conditions were used for immobilising LDH and MDH on Cellex-AE. 3. The effect of sodium borohydride reduction on the stability of YADH, LDH and MDH immobilised on Cellex-AE was studied. 4. The effect of pH on the stability of soluble YADH, LDH and MDH was studied. The results were compared to those for the three enzymes immobilised on Cellex-AE. 5. The effect of temperature on soluble YADH, LDH and MDH was compared to the effect of temperature on several immobilised derivatives of these enzymes. 6. YADH was immobilised on DEAE-cellulose. The pH variation of the kinetic parameters of the immobilised derivatives were compared to those of soluble YADH. 7. LDH was immobilised on both Cellex-AE and PEI. The kinetic parameters and stabilities of these two derivatives were compared. 8. LDH was immobilised on NP/3 Nylon Powder. The pH variation of the kinetic-parameters of the immobilised derivatives were compared to those of soluble LDH. 9. The change in equilibrium constant when YADH and LDH were immobilised on macromolecular supports was studied. A theory was developed to explain these changes.

The chemistry required for the immobilization of enzymes onto the inner surface of nylon tubing is demonstrated and conditions are optimised. Nylon tube immobilised enzymes are then introduced into continuous-flow systems so that their flow characteristics can be determined and the chemistry of immobilization best suited to continuous-flow analysis ascertained. The practical use of immobilized enzyme derivatives is evaluated in four separate methodologies end their stability and pH dependence is assessed.

NF-KB/Rel transcription factors and IKB proteins play a central role in the rapid induction of genes transcribed in response to a variety of extracellular stimuli. Signal induction results in the phosphorylation and ubiquitination of IKBalpha a prior to proteasomal degradation and release of NF-KB. The objective of this work was to identify residues within the N- and C-termini of IKBalpha which were important for the function of the protein, specifically the residues contacting the p65 subunit of NF- KB and those involved in the turnover of IKBalpha. In addition, the structure of the C-terminal region of IKBalpha was also examined to gain a better understanding of the functional properties of this domain. The identification of conserved stretches of acidic residues in the C-terminal region of IKBalpha prompted the suggestion that perhaps these amino acids were important for interacting with the positively charged nuclear localisation signal of the p65 subunit of NF- KB. Accordingly two regions, residues 284-286 and residues 300-302 (glutamic acid, aspartic acid, glutamic acid in both regions), were targeted for mutation (and referred to as the C-terminal mutants) to examine their role, if any, in IKBalpha -p65 association. A second set of mutants were generated following a protease sensitivity study on IKBalpha which revealed that residues 251 (tyrosine), 258 (tryptophan) and 275 (glutamic acid) were protected from digestion in the presence of p65. These amino acids were located in the low homology sixth ankyrin repeat of IKBalpha, thought to act as a flexible linker region between the highly conserved central five ankyrin repeats and the C-terminal region of the protein. Consequently, amino acids 258 and 275 were selected for mutation (referred to as the linker mutants). The in vitro characterisation of the C-terminal and linker mutants demonstrated that neither amino acids 258 and 275 nor amino acids 284-286 and 300-302 affected the ability of IKBalpha to interact with p65 homodimers, even under conditions of varying pH or ionic strength. However, residues 284-286 reduced the inhibitory capacity of IKBalpha with respect to p65 homodimers. The results indicated that the region of IKBalpha required for the inhibition of p65 DNA binding activity, possibly located in or around residues 284-286, was separable from the area of the protein responsible for association with p65. Attempts to phosphorylate the C-terminal and linker mutants in vitro using either casein kinase I or casein kinase II demonstrated that the C-terminal mutants were not efficiently phosphorylated by casein kinase II but were phosphorylated by casein kinase I. Both kinases were shown to phosphorylate wild-type IKBalpha and the linker mutants. Therefore, residues 284-286 and 300-302 were possibly important for the in vivo phosphorylation of IKBalpha through casein kinase II. The expression of the C-terminal and linker mutants from vectors transiently transfected into 293 cells revealed that residues 284-286 and residues 300-302 were required for either inducible or constitutive degradation of IKBalpha, but more likely constitutive turnover. All mutants appeared to undergo signal-induced ubiquitination. Furthermore, the mutants were capable of interacting with p65 and in a different cell line (Cos7 cells) all appeared to allow NF-KB-dependent transcription from a luciferase reporter. The final result was thought to be a consequence of different degradation characteristics existing within Cos7 cells compared to 293 cells. In the light of recent data, it was concluded that the C-terminal residues of IKBalpha were important for constitutive, rather than inducible turnover of IKBalpha.

A technique was developed for assaying amino acid: tRNA ligases extracted from tobacco XD cells grown in chemically defined medium (M-1D). The technique was based on the physiological enzymic reaction in which amino acid is aminoacylated to tRNA. tRNA was obtained from tobacco XD cells using a phenol extraction procedure. For two enzymes, arginine: tRNA ligase and leucine: tRNA ligase, assay conditions were optimised. Both enzymes had similar Km values for their cognate amino acids; were found to be unstable when stored at -10 and their activity was inhibited by ammonium sulphate and caesium chloride. During growth of tobacco XD cells, these two enzymes increased in activity. Amino acids appeared not to be involved in their regulation and attempts to perturb in vivo levels of aminoacyl-tRNA by use of amino acid analogues were unsuccessful. The use of the density labelling technique, which allows a distinction between pre-existing enzyme molecules and those that are newly synthesised, indicated that in M-ID both arginine; and leucine: tRNA ligases were synthesised de novo. Leucine: tRNA ligase was also degraded and therefore turned over as it increased in activity. The density labelling data did not allow a similar conclusion for arginine: tRNA ligase. During cell growth in nitrateless M-1D, there was no increase in the activity of arginine: and leucine: tRNA ligases, but both anzymes were found to be synthesised de novo. It was concluded, therefore, that they were both degraded and so turned over in nitrateless M-ID. Arginine: and leucine: tRNA ligases appeared to be synthesised from different amino acid pre-cursor pools and DEAE cellulose chromatography of enzyme extracts revealed the presence of three ligase species cognate for arginine but only two species cognate for leucine. The species cognate for arginine were in approximately equal proportions whereas one of the species cognate for leucine accounted for 80% of the total enzyme activity. The possibility that these multiple enzymic species might be responsible for the inability to demonstrate degradation of the arginine anzyme in M-1D was discussed. An accurate determination of the turnover rates of these/ these two enzymes could not be obtained due to the effects of re-cycling of total cell protein, but a comparison of turnover rates was attempted. The possible mode of regulation of these enzymes was discussed in relation to our observations and to those found in other systems.

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